1. Field of the Invention
The present invention relates to an antenna device preferably for use in a non-contact communication system, for example, an NFC (near field communication) system, and a communication terminal apparatus including the antenna device.
2. Description of the Related Art
Recently, an antenna device for use in a non-contact communication system using a band of 13.56 MHz is incorporated in a portable terminal. In such an antenna device, as disclosed in Japanese Patent Laid-Open Publication No. 2013-13144, Japanese Patent Laid-Open Publication No. 2008-205557 and Japanese Patent No. 4218635, a coil pattern spiraling on a plane is used as an antenna.
In order to connect both ends of the coil pattern spiraling on a plane to other circuits, normally, either of the ends is led to the outside through a via-hole conductor because it is necessary to insulate the ends from each other. However, it takes time and labor to form a via-hole conductor in a substrate, and the formation of a via-hole conductor complicates a manufacturing process.
There is a demand for an antenna device that can avoid degradation of the antenna characteristics. More particularly, in a case where a magnetic member, which is a component of an antenna device, is a sintered body, prevention of cracks of the sintered body is demanded in order to prevent degradation of the antenna characteristics. Also, it is demanded that an antenna device keeps good antenna characteristics even when the antenna device is located at a shorter distance from a communication counterpart, for example, another antenna.
As for an antenna device, further, the following features are required. A magnetic field generated from an antenna pattern is prevented from propagating to other conductor wires. In a bending process, the conductor wires easily bend, and stress concentration is avoided. Wiring disconnection is avoided, and connection reliability is improved. The strength is improved.